Electrolytic cell and method of assembling same

ABSTRACT

An electrolytic cell comprising a plurality of alternating, vertically disposed cathodes and anode plates, current lead-in metal bars connected to the lower ends of the anode plates, the metal bars and the lower ends of the anodes being embedded in and supported by a mass of electrically and thermally non-conducting rigid material such as concrete containing a chlorine resistant polyester resin. The anode plates may be comprised of a titanium type metal or alloy covered with an active layer containing a platinum group metal, alloy or compound. Included is means for feeding electrolyte to the cell while preventing unwanted flow of electricity through the feed ducts comprising a horizontal grooved disc for dividing the electrolyte into a plurality of radial droplet streams.

ite States. Patent [1 1 Giacopelli ELECTROLYTIC CELL AND METHOD OFASSEMBLING SAME Umberto Giacopelli, I Rosignano-Solvay/Livorno, ItalyFiled: Mar. 15, 1973 Appl. No.: 341,764

Inventor:

Foreign Application Priority Data Mar. 20, I972 Belgium H5282 U.S. Cl204/275, 204/242, 204/252, 204/263, 204/266, 204/286 Int. Cl 801k 3/00Field of Search 204/263, 266, 275, 286, 204/242, 252

References Cited UNITED STATES PATENTS 4/1970 Silsby, Jr 204/266 X8/1948 Stuart 204/266 3/1954 Silsby, Jr 204/275 X 3/1973 Berthoux et al.204/286 X 6/1969 Westerlund 204/275 FOREIGN PATENTS OR APPLICATIONS4/1971 Canada 204/266 l,l27,484 9/1968 Great Britain 204/266 PrimaryExaminer.lohn H. Mack Assistant Examiner-W. I. Solomon Attorney, Agent,or Firm-Robert E. Burns; Emmanuel J. Lobato; Bruce L. Adams [57]ABSTRACT An electrolytic cell comprising a plurality of alternating,vertically disposed cathodes and anode plates, current lead-in metalbars connected to the lower ends of the anode plates, the metal bars andthe lower ends of the anodes being embedded in and supported by a massof electrically and thermally non-conducting rigid material such asconcrete containing a chlorine resistant polyester resin. The anodeplates may be comprised of a titanium type metal or alloy covered withan active layer containing a platinum group metal, alloy or compound.Included is means for feeding electrolyte to the cell while preventingunwanted flow of electricity through the feed ducts comprising ahorizontal grooved disc for dividing the electrolyte into a plurality ofradial droplet streams.

15 Claims, 8 Drawing Figures t i i h PATENTEL wuv 1 21974 SHEEI 1 0F 6FIG. I

PATENTEL 2 3.847. 783

sum aor e PATIENIE NOV 1 21974 Fla; 7

ELECTROLYTIC CELL AND METHODOF ASSEMBLING SAME BACKGROUND OF THEINVENTION The present invention relates to improvements in electrolyticcells with vertical electrodes, for example, cells for the manufactureof chlorate or hypochlorite and diaphragm cells for the manufacture ofchlorine.

In the electrolysis of alkali metal halide, cells with graphite anodesare being replaced by'cells in which the anodes are thin plates of afilm forming material covered by an active layer.

In the present specification, by film forming material is meant amaterial of high electrical conductivity which, in the presence of theelectrolyte, spontaneously forms on itself an impermeable film which hasa very high electrical resistance. In practice, the film formingmaterials used in electrolysis are metals of the titanium type, forexample titanium, tantalum and niobium,or alloys of metals of this type.

The film forming material may constitute the whole of the anode plate orit may forman impermeable surface layer deposited on a support made of acheaper material such as copper.

The aforesaid active layer may contain a metal of the platinum group,i.e., platinum, palladium, ruthenium, rhodium, osmium or irridium, inthe form of a free metal, an alloy of these metals, or a compound (forexample an oxide) of at least one of these metals.

The advantages of metal anodes over graphite anodes are numerous andwell known: better electrical conductivity, higher mechanical strength,less cumbersome, no contamination of the electrolyte nor overloading ofthe diaphragm.

An important problem to be resolved in the construction of cells withvertical metal anodes lies in keeping the anodes in alignment in theinterior of the cell and in connecting them to a current lead. Onesolution which has been proposed is that customarily used for graphiteanodes, which consists in immersing the lower part of the anodes in amass of molten metal (normally lead or a lead alloy) which, afterfreezing, is covered by a protective layer against the corrosive actionof the electrolyte, for example, by a layer of bitumen. This method isnevertheless difficultto apply in the case of metal anodes, becauseduring solidification and cooling of the mass of metal large internalstrains develop which can cause deformation of the anode plates. Thedeformation of the anode plates interferes with the internal geometry ofthe cell by destroying the uniformity of the anode-cathode distances.

In order to resolve this difficulty it has been proposed in British Pat.Specification No. 1181659 to employ metal anodes in the form of a box,reinforced by cross braces and optionally provided with channels formingexpansion joints.

The manufacture of metal anodes of this type is more expensive.Furthermore the use of metal anodes in the form of a box cancels theaforementioned advantage of thin anodes as being less cumbersome in thecell.

The solution proposed in British Pat. Specification No. 1125493avoidsthese disadvantages. In the electrolytic cell described in thatpatent, the anodes are single metal plates or rows of single metalplates which are bolted, riveted or welded to a horizontal metal plateforming the base of the cell. This plate is made of a metal of thetitanium typeto form a currentlead to the anodes and to resist thecorrosive action of the electro lyte by spontaneous formation of animpermeable protective film.

The use of a film forming metal plate as the base of the cell is acostly solution. Furthermore, it necessitates firm anchorage of thisplate on a sub-foundation of concrete to avoid deformation-of the plateduring use of the cell. This deformation of the plate aided by theinternal stresses of thermal origin which arise during operation of thecell, causes lateral displacements of the anodes between the cathodes.Such defonnation of the metal plate supporting the anodes is alsoencouraged by the temperature variations to which it is submitted duringshutdown periods.

SUMMARY OF THE INVENTION A primary object of the present invention is toprovide a novel electrolysis cell which overcomes the above-mentioneddisadvantages of prior art cells. Another principal object of theinvention is to provide a novel method for constructing an electrolysiscell.

Briefly, an electrolytic cell of the invention comprising cathodesalternating with anodes, wherein each anode consists of a single metalplate or a row of metal plates in prolongation of one another. Eachplate has its two faces made of a film-forming material and coated atleast partly with a layer comprising a metal or a compound of a metal oftheplatinum group. The faces of the anode plates are substantiallyvertical and substantially parallel, and the lower portion of each plateis fixed to a pedestal forming the base of the cell and is connected toacurrent lead. The current lead comprises an array of horizontal metalbars, each bar extending between a neighboring pair of anodes and beingclamped between these anodes by a clamping means. The lower portions. ofthe. anode plates, the metal bars and the clamping means are embedded inand sealed in a mass of electrically and thermally nonconducting rigidmaterial which constitutes the pedestal and retains the platesvertically and laterally. The metal bars also serve as spacers betweenthe plates or the rows of plates which constitutethe anodes.

One advantage of a cell according to the invention resides in thepossibility of using for the metal bars constituting the current lead ametal of better electrical conductivity and lower cost than the filmforming metals, for example copper or aluminum. These bars are. ineffect isolated from the electrolyte by the aforesaid mass ofnon-conducting rigid material.

Another advantage of the invention results from em bedding the anodeplates in a mass of thermally nonconducting material. This mass, whichserves to retain the anode plates vertically and laterally, undergoes.

only moderate heating during operation of the cell, so that there is norisk of it deformingor cracking in service, nor of causing deformationof the anode plates. A cell according to the invention is thereforeadapted for using, as the anodes, unit metal plates or rows of unitmetal plates that are thin, and the cell may have anarrow anode-cathodegap.

In comparison to known cells, cells according to the invention have theappreciable advantages of reduced size and higher energy yield.

In the cell according to the invention, it is advantageous to make themass of embedding material leakproof andresistant to corrosion by theelectrolyte.

In a preferred form of the invention, conceived so as to still furtherreduce the internal stresses in the body of the sealing mass, the anodesconsisting of single plates or rows of plates are divided into severalsuccessive groups. The plates of each of these groups are clamped to thecorresponding metal bars lying between them, independently of the platesof the other groups, which are themselves clamped to their correspondingmetal bars.

By reducing the internal stresses in the mass of embedding material theaforesaid preferred embodiment of the cell allows the use of a largenumber of anodes and, consequently, the construction of monopolar cellsof large capacity and power. This embodiment of the cell also restrictsdamage to the current lead-in bars caused by occasional infiltration ofelectrolyte into the mass of embedding material.

In another advantageous embodiment of the invention, also conceived witha view to reducing the effect of internal stresses in the mass ofmaterial surrounding the metal bars, the assembly formed by these bars,the lower portion of the anode plates, and the clamping means which holdthe bars and the plates together is enclosed in a resilient membrane. Byvirtue of its elastic properties this membrane absorbs an appreciableproportion of the expansion stresses of the metal bars. Preferably, themembrane is leak proof and made of a material which is resistant tocorrosion by the electrolyte to protect the metal current lead-in barsagainst occasional infiltration of electrolyte into the mass ofembedding material.

In carrying out the present method of assembling a cell, before makingthe pedestal in which the anode plates and the current lead-in bars arefixed, at least two horizontal joists are placed on a foundation,suitably of reinforced concrete, and the anode assemblies are madeseparately by clamping the vertically disposed anode plates at theirlower edges to interposed horizontal current lead-in bars. The anodeassemblies are then placed across the horizontal joists, and thepedestal is formed by pouring an electrically and thermallynon-conducting embedding material around the joists, the current lead-inbars, and the lower parts of the anode plates so that the embeddingmaterial forms the pedestal after setting and hardening and then retainsthe anode plates vertically and laterally.

The invention will be further understood with reference to theaccompanying drawings, which represent by way of example severalembodiments of cells according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows in transverse elevation,partially cut away, one embodiment of a cell according to the invention.

FIG. 2 is a longitudinal elevation, partially cut away, of the cellshown in FIG. 1.

FIG. 3 shows on a larger scale a detail of FIG. 2.

FIGS. 4 and 5 show respectively in plan and in elevation an anodeassembly of the cell of FIGS. 1 and 2.

FIG. 6 is on a larger scale a partial section in the plane VIVI of FIG.4.

FIG. 7 shows on a larger scale a detail of FIG. 2 in elevation,partially cut away.

FIG. 8 is a partial transverse section of the foundation and the anodeassemblies of the cell of FIGS. 1 and 2 before pouring the mass whichforms the pedestal.

DETAILED DESCRIPTION OF THE INVENTION In the Figures, like parts havebeen numbered alike. The embodiments shown in the Figures relate todiaphragm cells for the manufacture of chlorine.

Referring to the drawings and more particularly to FIGS. 1 and 2, thecell comprises, on a foundation 1 of reinforced concrete supported byinsulators 2, a pedestal 3 forming the base 4 of the cell. The anodesare fixed vertically to the pedestal 3 by their lower end portions. Theyeach comprise a row of flat plates 5 made of titanium, coated over atleast part of their two faces by a layer of a platinum group metal,alloy or compound. The coating material may advantageously comprisemixed crystals of ruthenium dioxide and titanium dioxide.

The periphery of the pedestal 3 carries a cathode casing 6 made ofsteel, with an interposed sealing joint 7. The casing 6 supportsforaminous steel structure shaped to form cathode pockets 8 which extendbetween the adjacent rows of anode plates 5, and the foraminous steelstructure is covered with a diaphragm (not shown in the Figures).

A cover 9 of polyester is placed on the cathode casing 6 with aninterposed sealing joint 10 and is firmly held on the casing by clamps11 (FIG. 3).

A brine inlet conduit 12 extends downwardly through the top of cover 9to a brine distributor 13 which will be described later. At the top ofthe cover there is also an outlet pipe 14 for escape of chlorineproduced at the anodes. A liquid level indicator 15 is positioned at oneside of the cover as seen in FIG. 2.

The upper end of cathode casing 6 is connected to a pipe 16 for removalof hydrogen produced in the cathode pockets and to a hydraulic safetyvalve 17 or a similar safety device for avoiding excessive hydrogenpressure in the cell.

At its lower end the cathode casing 6 communicates with a pipe 18 forremoval of caustic liquor formed in the cathode pockets. An inverted Utube 19 is connected to pipe 18 by a joint 50 which allows theinclination of the U tube round the axis of pipe 18 to be varied atwill.

According to the invention the rows of anode plates 5 are supported inthe pedestal 3, which is constituted by a mass of a thermally andelectrically nonconducting rigid material. This mass making up thepedestal 3 may advantageously be made of concrete containing as a bindera polyester resin which is resistant to chlorine, for example Atlacresin (trademark). It may alternatively be made of another electricallyand thermally non-conducting material which is capable of sealing theanode plates 5 and retaining them vertically and laterally. If there isany risk of the material employed suffering from corrosion by theelectrolyte it may be covered by a layer of leak proof material which isinert towards the electrolyte, such as a layer of bitumen.

The rows of anode plates 5 are also connected to a current lead.According to the invention, this current lead comprises metal bars 20,which are interposed between the rows of anode plates 5 and are imbeddedin the mass of the pedestal 3.

In the direction perpendicular to the anode plates 5 the rows of platesare preferably divided into several groups of rows each group beingseparately connected to the respective current lead-in bars 20independently of the other groups to form within the electrolytic cellseveral distinct anode assemblies, for example, five anode assemblies inthe embodiment of FIG. 2.

FIGS. 3, 4 and 5 show one of these anode assemblies. This assemblycomprises, by way of example, five rows of three anode plates 5. Betweenthese five rows of plates 5 are interposed respectively four metal barsof rectangular cross-section, which extend horizontally throughout thelength of the lower portion of the plates 5. The bars 20 and the plates5 are firmly clamped to each other by means of nuts 21 screwed onto thethreaded rods 22 (FIG. 6) which pass through the bars and the plates.Small horizontal bars 23, made of metal, are advantageously placedbetween the nuts 21 and the plates 5 in each end row of the anodeassembly, so as to improve the contact of the anode plates with the bars20 and to avoid a deformation of these plates.

Since the bars 20 serve as the current lead to the anode plates 5 theyshould be made of a metal of good electrical conductivity. They may bemade of electrolytic copper, because they are effectively kept apartfrom the electrolyte by the large mass of the pedestal 3 which surroundsthem.

In order to strengthen the anchorage of the anode assembly in thepedestal 3, the metal bars 20 may optionally be perforated with orifices24 which are filled with the material of the pedestal 3.

During operation of the electrolytic cell, each anode assembly issupplied with current by means of the bars 20, of which one extremityextends outside the pedestal 3 and is connected to a current source (notshown).

With the aim of reducing the electrical resistances of the contactbetween the bars 20 and the anode plates 5, it is preferable that thethreaded rods 22 be made of a metal which has a linear coefficient ofthermal expansion less than that of the metal of the bars 20, forexample the rods 22 may be made of steel when the bars 20 are copper.With this arrangement, when the cell is operating, the differentialthermal expansion of the bars 20 and the threaded rods 22 increases theclamping force of the plates 5 between the bars 20.

In one embodiment of the cell according to the invention, the ends ofthe bars 20 which are downstream with respect to the direction of flowof electric current in these bars terminate short of the correspondingend of the row of plates 5 of the anode assembly. In order to maintainthe spacing between the remaining ends of these plates and to ensure therigidity of the anode assembly, spacer sleeves 25 (FIGS. 4 and 6) areinterposed between theseplates 5 and clamped between them by means ofnuts 21 screwed on the threaded rods 22 which pass through plates 5 andsleeves 25. This particular embodiment of the cell according to theinvention economizes in metal for the bars 20 by taking account of thefact that the current density in the downstream zone of the bars is muchlower than that in the upstream zone.

According to another feature of the invention, the lower portion of theanode plates 5, the bars 20,- the rods 22, the nuts 21 and the sleeves25 are enclosed in a resilient membrane 26 (FIG. 3) which is preferablyleak proof and made of a material resistant to corrosion by theelectrolyte. This membrane 26, which may for example be made ofplasticized polyvinyl chloride, reduces the internal stresses in themass of the pedestal 3 during operation of the cell. Furthermore, whenit is leak proof and resistant to corrosion, it protects the metal bars20 against the eventuality'of the electrolyte infiltrating through thepedestal 3.

The adjacent anode plates 5 of each anode assembly may be fastened attheir upper edge to projections 27 fixed to cross members 28 (FIGS. 1and 2) so as to maintain a constant spacing between the plates 5 and thecathodes 8 and to prevent lateral bending of the plates.

The cell shown in FIGS. 1 and 2 is equipped with a brine distributor 13at the discharge end of the electrolyte inlet pipe 12. This distributorI3 is shown in detail in FIG. 7. Its purpose is to create a very highresistance v in the path of any current shunted by way of the commonelectrolyte feed vessel of a cell room.

According to the invention, the distributor 13 comprises an overflowvessel 30 into which the feed conduit 12 extends and which is supportedon a substantially horizontal disc 29. The upper edge of the vessel 30is advantageously serrated so as to split up the flow of v electrolytespilling over from the vessel 30. For the same purpose the upper face ofthe disc 29 preferably has radial grooves 31 to ensure a more uniformdistribution of the electrolyte flowing over from this disc into thecell. The overflow vessel 30 is held axially on the disc 29 by means ofseveral radial struts 32 fixed to the vessel 30 and to the disc 29, forexample, by weldmg.

The distributor assembly l3 is held in the cell by a cylinder 33 fixedto the radial struts 32 and to the cell cover 9, for example, bywelding.

The distributor l3 and the inlet pipe 12 may be made of chlorinatedpolyvinyl chloride or another material which is inert to the electrolyteand the products of electrolysis.

The distributor shown in FIG. 7 has the dual advantages of renderingnegligible the loss of current shunted by way of the common electrolytefeed vessel and of forming a hydraulic seal against accidental escape ofchlorine out of the cell by way of inlet pipe 12.

Table I lists the results of two tests involving electrolysis of a brinein a diaphragm cell according to this invention. The cell used wassimilar to the embodiment illustrated in the attached drawings anddescribed hereabove. It comprised five anode assemblies as definedhereabove. In each anode assembly, each anode was constituted of a rowof flat titanium plates having a thickness of about 2 mm and coated, onboth faces, with a layer of ruthenium dioxideand titanium dioxide. Theplates were clamped vertically between horizontal current lead-in bars.'Ihese bars and the lower portion of the anode plates were enclosed in amembrane made of plasticized polyvinyl chloride. The pedestal 3 of thecell was made of concrete containing a polyester resin able to resistcorrosion by chlorine.

The total active anodic surface of the cell was approximately 26 m Theanode-cathode distance was about 13 mm.

It has been ascertained that the electrical resistance of the contactassembly of the anodic plates clamped between the bars did not increaseduring a working time of about 9 months, which confirms that this anodeassembly has not been damaged during electrolysis.

The electrolytic cell shown in FIGS. 1 and 2 may be constructed in thefollowing manner.

A foundation 1 for the cell is first constructed and is optionallysupported on insulators 2. The foundation 1 is usually made ofreinforced concrete. At least two horizontal joists 47 (FIG. 8) are thenplaced on the foundation 1 for supporting the anode assemblies of thecell. These joists are placed parallel to each other in the longitudinaldirection of the cell (across the drawing of FIG. 2).

The joists 47 are suitably made of the same material as thatconstituting the pedestal 3, for example, concrete with a polyesterbinder. They may however be made of another material, for example metal.The joists 47 are provided with transverse projections 48 on their uppersurface, separated from each other by a distance substantially equal tothe total width of each anode assembly without the nuts 21.

The anode assemblies are separately constructed before installation inthe cells by putting together the anode plates 5, the current lead-inbars 20, the small bars 23 and, if required, the spacer sleeve 25, bymeans of the threaded rods 22 and nuts 21 (FIGS. 4 and 5).

The rigid anode assemblies are then placed on the joists 47 between theprojections 48. A form is placed on the foundation 1 around the joists47 and the lower part of the anode assemblies that is supported by thesejoists. The material for embedding the joists 47 and the lower part ofthe anode assemblies is then poured into the form. When the mass has setand hardened the form is removed.

A thermally and electrically non-conducting material is employed for theaforesaid mass of embedding material which, after setting and hardening,constitutes the pedestal 3 of the cell, in which the anode assembliesare sealed.

When the material of pedestal 3 has set and hardened and the form hasbeen removed, a cathode casing 6 is placed on the pedestal 3 with aninterposed sealing joint 7 which is resistant to the electrolyte. Acover 9 is then placed on the cathode casing 6 with another interposedsealing joint 10.

I claim:

1. An electrolytic cell comprising a plurality of cathodes alternatingwith a plurality of generally vertical metal anode plates over apedestal, said anode plates having each coated thereon an active layercontaining a platinum group metal or metal compound, current supplymeans to said anode plates, comprising an array of generally horizontalmetal bars, each bar extending between the lower ends of a neighboringpair of anode plates, and clamping means to clamp said anode plates andmetal bars together to form an anode assembly, said metal bars, lowerends of the anode plates and clamping means being embedded and sealed ina mono lithic mass of electrically and thermally nonconducting rigidmaterial, whereby said mass forms at least part of the aforesaidpedestal and retains the anode plates vertically and laterally.

2. An electrolytic cell according to claim I, wherein said rigidmaterial is concrete containing a chlorine resistant polyester resin.

3. An electrolytic cell according to claim 1, wherein said anode plateseach comprise an array of metal plates disposed in prolongation of oneanother.

4. An electrolytic cell according to claim 1, wherein said clampingmeans comprise metal rods passing through said bars and said neighboringanode plates, said rods having a linear coefficient of thennal expansionlower than that of said metal bars, and fastening means at the ends ofsaid rods.

5. An electrolytic cell according to claim 1, wherein each metal barterminates short of the ends of the neighboring anode plates clampedthereto.

6. An electrolytic cell according to claim 5, further comprising aspacer extending between the portions of said neighboring anode platesextending beyond the end of each metal bar.

7. An electrolytic cell according to claim 1, wherein at least some ofsaid metal bars are provided with transverse openings extendingtherethrough, said openings being filled by portions of said mass ofelectrically and thermally non-conducting rigid material.

8. An electrolytic cell according to claim 1, wherein said anode platesand metal bars, clamped together, are distributed into a plurality ofindependent anode assemblies, which are retained remote from one anotherby a portion of said mass.

9. An electrolytic cell according to claim 8, wherein the metal bars,the lower portions of the anode plates, and the clamping means of eachunit assembly are onclosed in a resilient membrane.

10. An electrolytic cell according to claim 9, wherein said membrane isleak proof and resistant to corrosion by electrolyte in the cell.

11. An electrolytic cell according to claim 10, wherein said membrane ismade of plasticized polyvinyl chloride.

12. An electrolytic cell according to claim 1, further comprising a cellcover, an inlet pipe for admission of electrolyte passing through saidcover, and a horizontal disc provided with radial channels fordistributing electrolyte positioned vertically below the discharge endof said inlet pipe.

13. An electrolytic cell according to claim 12, further comprising anoverflow vessel disposed around the discharge end of said inlet pipe andsupported upon said horizontal disc.

14. In a process for assembling an electrolytic cell having a pluralityof vertically disposed, alternating cathodes and anodes, wherein theimprovement comprises initially preparing at least one anode assembly byclamping a plurality of metal plates at their lower edges to interposedcurrent lead-in bars, placing at least two horizontal joists on afoundation, positioning each anode assembly on and across the joists,and embedding the current lead-in bars and the lower ends of the anodeplates in a monolithic mass of electrically and thermally non-conductivematerial, and hardening said material to support and retain the anodeplates in a substantially vertical position.

15. In a process according to claim 14, further comprising positioningat least two anode assemblies on and across the horizontal joists, andproviding said joists with at least one transverse projection having athickness substantially equal to the distance between two neighboringanodes.

1. An electrolytic cell comprising a plurality of cathodes alternatingwith a plurality of generally vertical metal anode plates over apedestal, said anode plates having each coated thereon an active layercontaining a platinum group metal or metal compound, current supplymeans to said anode plates, comprising an array of generally horizontalmetal bars, each bar extending between the lower ends of a neighboringpair of anode plates, and clamping means to clamp said anode plates andmetal bars together to form an anode assembly, said metal bars, lowerends of the anode plates and clamping means being embedded and sealed ina monolithic mass of electrically and thermally nonconducting rigidmaterial, whereby said mass forms at least part of the aforesaidpedestal and retains the anode plates vertically and laterally.
 2. Anelectrolytic cell according to claim 1, wherein said rigid material isconcrete containing a chlorine resistant polyester resin.
 3. Anelectrolytic cell according to claim 1, wherein said anode plates eachcomprise an array of metal plates disposed in prolongation of oneanother.
 4. An electrolytic cell according to claim 1, wherein saidclamping means comprise metal rods passing through said bars and saidneighboring anode plates, said rods having a linear coefficient ofthermal expansion lower than that of said metal bars, and fasteningmeans at the ends of said rods.
 5. An electrolytic cell according toclaim 1, wherein each metal bar terminates short of the ends of theneighboring anode plates clamped thereto.
 6. An electrolytic cellaccording to claim 5, further comprising a spacer extending between theportions of said neighboring anode plates extending beyond the end ofeach metal bar.
 7. An electrolytic cell according to claim 1, wherein atleast some of said metal bars are provided with transverse openingsextending therethrough, said openings being filled by portions of saidmass of electrically and thermally non-conducting rigid material.
 8. Anelectrolytic cell according to claim 1, wherein said anode plates andmetal bars, clamped together, are distributed into a plurality ofindependent anode assemblies, which are retained remote from one anotherby a portion of said mass.
 9. An electrolytic cell according to claim 8,wherein the metal bars, the lower portions of the anode plates, and theclamping means of each unit assembly are enclosed in a resilientmembrane.
 10. An electrolytic cell according to claim 9, wherein saidmembrane is leak proof and resistant to corrosion by electrolyte in thecell.
 11. An electrolytic cell according to claim 10, wherein saidmembrane is made of plasticized polyvinyl chloride.
 12. An electrolyticcell according to claim 1, further comprising a cell cover, an inletpipe for admission of electrolyte passing through said cover, and ahorizontal disc provided with radial channels for distributingelectrolyte positioned vertically below the discharge end of said inletpipe.
 13. An electrolytic cell according to claim 12, further comprisingan overflow vessel disposed around the discharge end of said inlet pipeand supported upon said horizontal disc.
 14. In a process for assemblingan electrolytic cell having a plurality of vertically disposed,alternating cathodes and anodes, wherein the improvement comprisesinitially preparing at least one anode assembly by clamping a pluralityof metal plates at their lower edges to interposed current lead-in bars,placing at least two horizontal joists on a foundation, positioning eachanode assembly on and across the joists, and embedding the currentlead-in bars and the lower ends of the anode plates in a monolithic massof electrically and thermally non-conductive material, and hardeningsaid material to support and retain the anode plates in a substantiallyvertical position.
 15. In a process according to claim 14, furthercomprising positioning at least two anode assemblies on and across thehorizonTal joists, and providing said joists with at least onetransverse projection having a thickness substantially equal to thedistance between two neighboring anodes.